Printing and display device

ABSTRACT

A printing and display device comprising a flat panel display; a printer, including a printhead for printing onto paper; a multi-sheet paper holder; a paper sheet separator configured to separate a single paper sheet from the paper in the paper holder for supply to the printhead.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.10/803,077 filed on Mar. 18, 2004, the contents of which are hereinincorporated by reference.

FIELD OF INVENTION

The present invention relates to an integrated printing and flat paneldisplay unit.

The invention has been developed primarily as an integrated peripheralunit that is connectable to a personal computer such as Macintosh or IBMcompatible PC. However, it will be appreciated by those skilled in theart that the invention is not limited to these applications.

BACKGROUND

Flat panel displays are known. A popular technology presently in use isthe Thin Film Transistor (TFT) Liquid Crystal Display (LCD), whichcomprises an array of liquid crystal pixel elements driven by respectivethin film transistors. In each element, liquid crystal is sandwichedbetween glass plates. A backlight is positioned behind the LCD layerrelative to a position from which the display will be viewed. Apolarizing screen is placed between the backlight and the LCD layer, andanother polarizing screen is positioned on the other side of the LCDlayer. The polarizing screens are orientated to be orthogonallypolarizing with respect to each other.

Using the corresponding TFT to alter a voltage applied to the liquidcrystal element causes a change in its crystalline structure thatcorrespondingly alters the polarization of light passing through theelement from the backlight. This change in polarization causes acorresponding change in the amount of light transmitted through thepolarizing screens and LCD element.

Multiple colors are dealt with by providing each pixel with multiple LCDpixel elements (usually red, green and blue) that can individually becontrolled for each pixel, thereby allowing various color combinations.

The design and operation of TFT LCD screens is well known to thoseskilled in the art and so is not described in more detail in thisdocument.

Typically, flat panel displays, including TFT LCD displays, are moreexpensive than Cathode Ray Tube (CRT) display of comparable performance.However, the relative lightness and compactness of flat panel displays(particularly in terms of front to back depth) make them particularlysuitable for situations where a small footprint is desirable. They areubiquitous in laptop computers, and have come down in price sufficientlyfor them to be attractive to many desktop computer users. The relativelyshallow front to back depth means that the display can be pushed backfurther from the user than would be possible with a CRT in manysituations, thereby allowing better viewing comfort. Flat panel displaysalso enable a user to utilize considerably smaller areas than would bepossible with an equivalent CRT display, which can be important insituations where a wall, partition or divider is located close to a workarea in which the display is to be situated.

Often, computer users wish to print a hard copy of documents, images,web pages and the like. Usually, a printer is provided as a peripheraldevice that can be connected to the computer using a suitable cable.Alternatively, the computer can be connected via a Local Area Network(LAN) or other communications network. Printers can be bulky, and tendto take up additional space in a user's work area. Where space is at apremium, such printers can be intrusive or at least inconvenient. Inmany cases where a flat panel display is selected, space is already at apremium, so printers can exacerbate the problem.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided astand alone monitor for connecting to an external computer, the monitorcomprising:

-   -   a housing detached from the external computer;    -   a flat panel display disposed in the housing for displaying        image data provided by the external computer;    -   a pagewidth inkjet printhead for printing print data provided by        the external computer onto a paper sheet, the pagewidth inkjet        printhead being disposed in the housing behind the flat panel        display as viewed by a user; and    -   a connection configured to allow releasable operative connection        of the external computer to the monitor, for receiving the image        data and print data.

Other aspects are also disclosed.

BRIEF DESCRIPTION OF DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic of document data flow in a printing system;

FIG. 2 is a more detailed schematic showing an architecture used in theprinting system of FIG. 1;

FIG. 3 is a data representation of page element used in the printingsystem of FIG. 1,

FIG. 4 is a schematic showing CMOS drive and control blocks for use withthe printer of FIG. 1;

FIG. 5 is a schematic showing the relationship between nozzle columnsand dot shift registers in the CMOS blocks of FIG. 4;

FIG. 6 is a more detailed schematic showing a unit cell and itsrelationship to the nozzle columns and dot shift registers of FIG. 5;

FIG. 7 is a circuit diagram showing logic for a single printer nozzle inthe printer of FIG. 1;

FIG. 8 is a perspective view of a flat panel display incorporating aprinter, in accordance with the invention;

FIG. 9 is a perspective view of the flat panel display of FIG. 8, whilstprinting a page;

FIG. 10 is a rear perspective view of the flat panel display of FIG. 8;

FIG. 11 is a front elevation of the flat panel display of FIG. 9;

FIG. 12 is a right-hand side elevation of the flat panel display of FIG.9;

FIG. 13 is a plan view of the flat panel display of FIG. 9;

FIG. 14 is a left-hand side elevation of the flat panel display of FIG.9;

FIG. 15 is a rear elevation of the flat panel display of FIG. 9;

FIG. 16 is a perspective exploded view of the flat panel display of FIG.8;

FIG. 17 is a rear perspective view of the flat panel display of FIG. 8with the stand detached;

FIG. 18 is a rear perspective view of the flat panel display of FIG. 8with the rear cover removed;

FIG. 19 is a rear perspective view of the flat panel display of FIG. 8with the shields removed;

FIG. 20 is a rear perspective view of the flat panel display of FIG. 8showing the core electrical and electronic components;

FIG. 21 is a perspective view of interconnected printed circuit boardsused in the flat panel display of FIG. 8;

FIG. 22 is a perspective view of the print engine used in the flat paneldisplay of FIG. 8;

FIG. 23 is a perspective view of the print engine of FIG. 22, with somecomponentry removed to reveal the printhead;

FIG. 24 is a vertical section along the centerline of the flat paneldisplay of FIG. 8;

FIG. 25 is an enlarged detail view of the vertical section of FIG. 24;

FIG. 26 is an enlarged detail view of a vertical section of a secondembodiment of a flat panel display incorporating a duplex printhead, inaccordance with the invention;

FIG. 27 is a vertical section along the centerline of a third embodimentof a flat panel display incorporating a multi-sheet paper feeder, inaccordance with the invention;

FIG. 28 is an enlarged detail view of the vertical section of FIG. 27;

FIG. 29 is a rear perspective view of an alternative embodiment of aflat panel display including power and data connections in its base, inaccordance with the invention;

FIG. 30 is a rear perspective view of an alternative embodiment of aflat panel display including a power input, data inputs and data outputsin its base, in accordance with the invention;

FIG. 31 is a rear perspective view of an alternative embodiment of aflat panel display including power and data connections in its base andan ink cartridge in its mounting plate, in accordance with theinvention;

FIG. 32 is a rear perspective view of an alternative embodiment of aflat panel display including an ink cartridge, a power input and dataconnections in its base, in accordance with the invention;

FIG. 33 is a perspective view of a bi-lithic printhead for use in theflat panel display of FIG. 8;

FIG. 34 is a rear perspective view of the bi-lithic printhead of FIG.33;

FIGS. 35(A) to 35(D) show a side elevation, plan view, opposite sideelevation and reverse plan view, respectively, of the bi-lithicprinthead of FIG. 33;

FIGS. 36 and 37 show enlarged end views of the bi-lithic printhead ofFIG. 33;

FIG. 38 shows an enlarged detail plan view of one end of the bi-lithicprinthead of FIG. 33;

FIG. 39 is a sectional view taken along line 45-45 in FIG. 38;

FIG. 40 is an enlarged detail perspective view of one end of thebi-lithic printhead of FIG. 33;

FIG. 41 is an enlarged detail perspective view of an opposite end of thebi-lithic printhead of FIG. 33;

FIG. 42 is an exploded perspective view of the bi-lithic printhead ofFIG. 33;

FIG. 43 is a sectional view taken along line 49-49 in FIG. 38;

FIG. 44 is a schematic view showing the components of the flat paneldisplay of FIG. 8;

FIG. 45 is a schematic view of a print engine chip incorporated in theflat panel display of FIG. 8;

FIG. 46 is a vertical sectional view of a single nozzle for ejectingink, for use with the invention, in a quiescent state;

FIG. 47 is a vertical sectional view of the nozzle of FIG. 46 during aninitial actuation phase;

FIG. 48 is a vertical sectional view of the nozzle of FIG. 57 later inthe actuation phase;

FIG. 49 is a perspective partial vertical sectional view of the nozzleof FIG. 48, at the actuation state shown in FIG. 48;

FIG. 50 is a perspective vertical section of the nozzle of FIG. 46, withink omitted;

FIG. 51 is a vertical sectional view of the of the nozzle of FIG. 50;

FIG. 52 is a perspective partial vertical sectional view of the nozzleof FIG. 46, at the actuation state shown in FIG. 47;

FIG. 53 is a plan view of the nozzle of FIG. 46;

FIG. 54 is a plan view of the nozzle of FIG. 46 with the lever arm andmovable nozzle removed for clarity;

FIG. 55 is a perspective vertical sectional view of a part of aprinthead chip incorporating a plurality of the nozzle arrangements ofthe type shown in FIG. 46.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

As shown in FIG. 1, in the preferred embodiment, the printing aspect ofthe invention is embodied in an A4/Letter printer 100 that printsdocuments supplied by a computer system 102. The computer system 102 isprogrammed to perform various steps involved in printing a document,including receiving the document (step 103), buffering it (step 104) andrasterizing it (step 106), and then compressing it (step 108) fortransmission to the printer 100.

The compressed, multi-layer page image is buffered (step 110) uponreceipt in the printer 100, then expanded (step 112). The expandedcontone layer is dithered (step 114) and then the black layer from theexpansion step is composited over the dithered contone layer (step 116).Coded data can also be rendered (step 118) to form an additional layer,to be printed (in the preferred form) using an infrared ink that issubstantially invisible to the human eye. The black, dithered contoneand infrared layers are combined (step 120) to form a page that issupplied to a printhead for printing (step 122). In the preferredembodiment, the printhead is a bi-lithic printhead configured to printin 6 colors in a pagewidth format, although the design can be adapted toprint using any desired number of colors, and can be monolithic orrequire multiple substrates depending upon implementation.

The preferred embodiment divides printer data into a high-resolutionbi-level mask layer for text and line art and a medium-resolutioncontone color image layer for images or background colors. Optionally,colored text can be supported by the addition of amedium-to-high-resolution contone texture layer for texturing text andline art with color data taken from an image or from flat colors. Thepreferred printing architecture, elements of which are described in moredetail below, generalises these contone layers by representing them inabstract “image” and “texture” layers which can refer to either imagedata or flat color data. This division of data into layers based oncontent follows the base mode Mixed Raster Content (MRC) model specifiedin ITU-T.44. Like the MRC base mode, the preferred printing architecturemakes compromises in some cases when data to be printed overlap. Inparticular, in the preferred form all overlaps are reduced to a 3-layerrepresentation in a process (collision resolution) embodying thecompromises explicitly.

As shown in FIG. 3, the central data structure for the preferredprinting architecture is a generalised representation of the threelayers, called a page element. A page element can be used to representunits ranging from single rendered elements emerging from a renderingengine up to an entire band of a print job. FIG. 3 shows a simplifiedUML diagram of a page element 300. Conceptually, the bi-level symbolregion selects between the two color sources, as described in moredetail below.

Printing Architecture

A more detailed description of the printing architecture will now bedescribed with reference to FIGS. 2 and 3. It will be appreciated thatthe components of the architecture 208 shown in FIG. 2 will typically bedevice dependent, in that they process the data into a form required bya software or hardware component further downstream.

In FIG. 2, a renderer 209 exists outside of the more general printersystem pipeline. Its purpose is to render files to be printed anddeliver rendered elements to the data receiver 210 of the pipeline,using an API (“Application Programming Interface”) exposed by the datareceiver 210 for that purpose. The rendered elements are delivered inorder according to the painter's algorithm, which is well known to thoseskilled in the art of image processing. The data passed in through theAPI is converted by the data receiver 210 into lists of dictionaries andpage elements for processing in later stages.

A collision resolver 211 accepts the simple page elements created by thedata receiver and creates a fully opaque “resolved” page element foreach intersection of a new element with the background and any elementsalready present. Fundamentally, the collision resolver guarantees thatthe entire page is tiled with opaque elements.

A stripper 212 divides a band of data into horizontally overlappingpieces. This need only be performed in the case where relatively wide orfast printers use multiple parallel devices in order to achieve therequired output dot-rate. In such cases, each horizontally overlappingpiece is fed into a corresponding device downstream. Where such datadivision is not required, the stripper 212 can be omitted.

Different printing configurations will require different configurationsof layers for delivery to the downstream hardware. A layer reorganiser213 converts 3-layer page elements to the appropriate 2- or 3-layer formfor the specific configuration. Again, there may be cases in which thisfunction is not required, in which case the layer organiser can beomitted.

A contone combiner 214 combines and clips the image and texture layersof all page elements in a strip into single image and texture layers, asrequired by downstream hardware.

A color converter 215 transforms the contone planes of all page elementsfrom the input color space to a device-specific color space (which isusually CMYK).

A mask combiner 216 performs the same operation on the mask layer as thecontone combiner performs on the contone layers. All elements areclipped to a strip boundary and drawn into a single mask buffer.

A densitometer 218 measures the density of the current page as apercentage of total possible density. This operation is necessary onlyin low-end printers with power supplies that may not be able to handle afully dense page at full speed.

A contone compressor 220 compresses the contone layers of all pageelements in order to reduce downstream memory and/or transmissionbandwidth requirements.

A mask formatter 222 converts the mask layer of page elements, which maybe represented as regions of placed symbol references, into the formexpected by a downstream mask decompressor.

A size limiter 224 ensures that all size limitations, for bands and forentire pages, are adhered to, by either dividing bands into smallerbands or by recompressing the data, repeating until the constraint issatisfied.

If data is to be transmitted to the printer between pipeline stages, aserialised form of the data structures is generated (in serialiser 226),transmitted, then deserialised (in deserialiser 228).

Within the printer, a distributor 230 converts data from a proprietaryrepresentation into a hardware-specific representation and ensures thatthe data for each strip is sent to the correct hardware device whilstobserving any constraints or requirements on data transmission to thesedevices. The distributor distributes the converted data to anappropriate one of a plurality of pipelines 232. The pipelines areidentical to each other, and in essence provide decompression, scalingand dot compositing functions to generate a set of printable dotoutputs.

Each pipeline 232 includes a buffer 234 for receiving the data. Acontone decompressor 236 decompresses the color contone planes, and amask decompressor 238 decompresses the monotone (text) layer. Contoneand mask scalers 240 and 242 scale the decompressed contone and maskplanes respectively, to take into account the size of the medium ontowhich the page is to be printed.

The scaled contone planes are then dithered by ditherer 244. In thepreferred form, a stochastic dispersed-dot dither is used. Unlike aclustered-dot (or amplitude-modulated) dither, a dispersed-dot (orfrequency-modulated) dither reproduces high spatial frequencies (i.e.image detail) almost to the limits of the dot resolution, whilesimultaneously reproducing lower spatial frequencies to their full colordepth, when spatially integrated by the eye. A stochastic dither matrixis carefully designed to be relatively free of objectionablelow-frequency patterns when tiled across the image. As such, its sizetypically exceeds the minimum size required to support a particularnumber of intensity levels (e.g. 16×16×8 bits for 257 intensity levels).

The dithered planes are then composited in a dot compositor 246 on adot-by-dot basis to provide dot data suitable for printing. This data isforwarded to data distribution and drive circuitry 248, which in turndistributes the data to the correct nozzle actuators 250, which in turncause ink to be ejected from the correct nozzles 252 at the correcttime. This process is described in more detail below.

The architecture 208 includes a mainly software-based computer systemportion prior to the serialiser 226, and a mainly hardware-based printerportion that is located within a printer remote from the computersystem, which includes everything from the deserialiser 228 onwards. Itwill be appreciated, however, that the indicated division betweencomputer system and printer is somewhat arbitrary, and variouscomponents can be placed on different sides of the divide withoutsubstantially altering the operation of the architecture as a whole. Itwill also be appreciated that some of the components in the architecture208 can be handled in hardware or software remotely from the maincomputer system and printer. For example, rather than relying on thegeneral-purpose processor of a personal computer, some of the componentsin the architecture can be accelerated using dedicated hardware.

SoPEC Device

In the preferred form, the hardware pipelines 232 are embodied in aSmall Office Home Office Printer Engine Controller (SoPEC), as shown inFIG. 2 and described in more detail below. The printer preferably alsoincludes one or more system on a chip (SoC) components, as well as theprint engine pipeline control application specific logic, configured toperform some or all of the functions described above in relation to theprinting pipeline.

As shown in FIG. 45, from the highest point of view a SoPEC deviceconsists of 3 distinct subsystems: a Central Processing Unit (CPU)subsystem 301, a Dynamic Random Access Memory (DRAM) subsystem 302 and aPrint Engine Pipeline (PEP) subsystem 303.

The CPU subsystem 301 includes a CPU 30 that controls and configures allaspects of the other subsystems. It provides general support forinterfacing and synchronizing the external printer with the internalprint engine. It also controls the low-speed communication to QA chips(which are described elsewhere in this specification). The CPU subsystem301 also contains various peripherals to aid the CPU, such as GeneralPurpose Input Output (GPIO, which includes motor control), an InterruptController Unit (ICU), LSS Master and general timers. The SerialCommunications Block (SCB) on the CPU subsystem provides a full speedUSB1.1 interface to the host as well as an Inter SoPEC Interface (ISI)to other SoPEC devices (not shown).

The DRAM subsystem 302 accepts requests from the CPU, SerialCommunications Block (SCB) and blocks within the PEP subsystem. The DRAMsubsystem 302, and in particular the DRAM Interface Unit (DIU),arbitrates the various requests and determines which request should winaccess to the DRAM. The DIU arbitrates based on configured parameters,to allow sufficient access to DRAM for all requesters. The DIU alsohides the implementation specifics of the DRAM such as page size, numberof banks and refresh rates.

The Print Engine Pipeline (PEP) subsystem 303 accepts compressed pagesfrom DRAM and renders them to bi-level dots for a given print linedestined for a printhead interface that communicates directly with up to2 segments of a bi-lithic printhead. The first stage of the pageexpansion pipeline is the Contone Decoder Unit (CDU), Lossless Bi-levelDecoder (LBD) and Tag Encoder (TE). The CDU expands the JPEG-compressedcontone (typically CMYK) layers, the LBD expands the compressed bi-levellayer (typically K), and the TE encodes Netpage tags for later rendering(typically in IR or K ink). The output from the first stage is a set ofbuffers: the Contone FIFO unit (CFU), the Spot FIFO Unit (SFU), and theTag FIFO Unit (TFU). The CFU and SFU buffers are implemented in DRAM.

The second stage is the Halftone Compositor Unit (HCU), which dithersthe contone layer and composites position tags and the bi-level spotlayer over the resulting bi-level dithered layer.

A number of compositing options can be implemented, depending upon theprinthead with which the SoPEC device is used. Up to 6 channels ofbi-level data are produced from this stage, although not all channelsmay be present on the printhead. For example, the printhead may be CMYonly, with K pushed into the CMY channels and IR ignored. Alternatively,the encoded tags may be printed in K if IR ink is not available (or fortesting purposes).

In the third stage, a Dead Nozzle Compensator (DNC) compensates for deadnozzles in the printhead by color redundancy and error diffusing of deadnozzle data into surrounding dots.

The resultant bi-level 6 channel dot-data (typically CMYK, Infrared,Fixative) is buffered and written to a set of line buffers stored inDRAM via a Dotline Writer Unit (DWU).

Finally, the dot-data is loaded back from DRAM, and passed to theprinthead interface via a dot FIFO. The dot FIFO accepts data from aLine Loader Unit (LLU) at the system clock rate (pclk), while thePrintHead Interface (PHI) removes data from the FIFO and sends it to theprinthead at a rate of ⅔ times the system clock rate.

In the preferred form, the DRAM is 2.5 Mbytes in size, of which about 2Mbytes are available for compressed page store data. A compressed pageis received in two or more bands, with a number of bands stored inmemory. As a band of the page is consumed by the PEP subsystem 303 forprinting, a new band can be downloaded. The new band may be for thecurrent page or the next page.

Using banding it is possible to begin printing a page before thecomplete compressed page is downloaded, but care must be taken to ensurethat data is always available for printing or a buffer under-run mayoccur.

The embedded USB 1.1 device accepts compressed page data and controlcommands from the host PC, and facilitates the data transfer to eitherthe DRAM (or to another SoPEC device in multi-SoPEC systems, asdescribed below).

Multiple SoPEC devices can be used in alternative embodiments, and canperform different functions depending upon the particularimplementation. For example, in some cases a SoPEC device can be usedsimply for its onboard DRAM, while another SoPEC device attends to thevarious decompression and formatting functions described above. This canreduce the chance of buffer under-run, which can happen in the eventthat the printer commences printing a page prior to all the data forthat page being received and the rest of the data is not received intime. Adding an extra SoPEC device for its memory buffering capabilitiesdoubles the amount of data that can be buffered, even if none of theother capabilities of the additional chip are utilized.

Each SoPEC system can have several quality assurance (QA) devicesdesigned to cooperate with each other to ensure the quality of theprinter mechanics, the quality of the ink supply so the printheadnozzles will not be damaged during prints, and the quality of thesoftware to ensure printheads and mechanics are not damaged.

Normally, each printing SoPEC will have an associated printer QA, whichstores information printer attributes such as maximum print speed. Anink cartridge for use with the system will also contain an ink QA chip,which stores cartridge information such as the amount of ink remaining.The printhead also has a QA chip, configured to act as a ROM(effectively as an EEPROM) that stores printhead-specific informationsuch as dead nozzle mapping and printhead characteristics. The CPU inthe SoPEC device can optionally load and run program code from a QA Chipthat effectively acts as a serial EEPROM. Finally, the CPU in the SoPECdevice runs a logical QA chip (ie, a software QA chip).

Usually, all QA chips in the system are physically identical, with onlythe contents of flash memory differentiating one from the other.

Each SoPEC device has two LSS system buses that can communicate with QAdevices for system authentication and ink usage accounting. A largenumber of QA devices can be used per bus and their position in thesystem is unrestricted with the exception that printer QA and ink QAdevices should be on separate LSS busses.

In use, the logical QA communicates with the ink QA to determineremaining ink. The reply from the ink QA is authenticated with referenceto the printer QA. The verification from the printer QA is itselfauthenticated by the logical QA, thereby indirectly adding an additionalauthentication level to the reply from the ink QA.

Data passed between the QA chips, other than the printhead QA, isauthenticated by way of digital signatures. In the preferred embodiment,HMAC-SHA1 authentication is used for data, and RSA is used for programcode, although other schemes could be used instead.

A single SoPEC device can control two bi-lithic printheads and up to sixcolor channels. Six channels of colored ink are the expected maximum ina consumer SOHO, or office bi-lithic printing environment, and include:

-   -   CMY (cyan, magenta, yellow), for regular color printing.    -   K (black), for black text, line graphics and gray-scale        printing.    -   IR (infrared), for Netpage-enabled applications.    -   F (fixative), to enable printing at high speed.

Because the bi-lithic printer is capable of printing so fast, a fixativemay be required to enable the ink to dry before the page touches thepage already printed. Otherwise ink may bleed between pages. Inrelatively low-speed printing environments the fixative may not berequired.

In the preferred form, the SoPEC device is color space agnostic.Although it can accept contone data as CMYX or RGBX, where X is anoptional 4th channel, it also can accept contone data in any print colorspace. Additionally, SoPEC provides a mechanism for arbitrary mapping ofinput channels to output channels, including combining dots for inkoptimization and generation of channels based on any number of otherchannels. However, inputs are typically CMYK for contone input, K forthe bi-level input, and the optional Netpage tag dots are typicallyrendered to an infrared layer. A fixative channel is typically generatedfor fast printing applications.

In the preferred form, the SoPEC device is also resolution agnostic. Itmerely provides a mapping between input resolutions and outputresolutions by means of scale factors. The expected output resolutionfor the preferred embodiment is 1600 dpi, but SoPEC actually has noknowledge of the physical resolution of the Bi-lithic printhead.

In the preferred form, the SoPEC device is page-length agnostic.Successive pages are typically split into bands and downloaded into thepage store as each band of information is consumed.

The following three tables show the constituents of each of the threedistinct subsystems which make up the SoPEC device. In particular, eachof the columns provide the unit acronym, the unit name and a descriptionof the functions performed by each unit.

Unit Subsystem Acronym Unit Name Description DRAM DIU DRAM Providesinterface for DRAM interface read and write access for the unit variousSoPEC units, CPU and the SCB block. The DIU provides arbitration betweencompeting units and controls DRAM access. DRAM Embedded 20 Mbits ofembedded DRAM. DRAM

Unit Subsystem Acronym Unit Name Description CPU CPU Central ProcessingUnit CPU for system configuration and control. MMU Memory ManagementUnit Limits access to certain memory address areas in CPU user mode. RDUReal-time Debug Unit Facilitates the observation of the contents of mostof the CPU addressable registers in SoPEC, in addition to some pseudo-registers in real time. TIM General Timer Contains watchdog and generalsystem timers. LSS Low Speed Serial Interfaces Low level controller forinterfacing with the QA chips GPIO General Purpose IOs General IOcontroller, with built-in Motor control unit, LED pulse units andde-glitch circuitry ROM Boot ROM 16 KBytes of System Boot ROM code ICUInterrupt Controller Unit General Purpose interrupt controller withconfigurable priority, and masking. CPR Clock, Power and Reset CentralUnit for controlling and block generating the system clocks and resetsand powerdown mechanisms PSS Power Save Storage Storage retained whilesystem is powered down USB Universal Serial Bus Device USB devicecontroller for interfacing with the host USB. ISI Inter-SoPEC InterfaceISI controller for data and control communication with other SoPECs in amulti-SoPEC system SCB Serial Communication Contains both the USB andISI Block blocks.

Unit Subsystem Acronym Unit Name Description Print PCU PEP controllerProvides external CPU with the Engine means to read and write PEPPipeline Unit registers, and read and write (PEP) DRAM in single 32-bitchunks. CDU Contone Decoder Unit Expands JPEG compressed contone layerand writes decompressed contone to DRAM CFU Contone FIFO Unit Providesline buffering between CDU and HCU LBD Lossless Bi-level Decoder Expandscompressed bi-level layer. SFU Spot FIFO Unit Provides line bufferingbetween LBD and HCU TE Tag Encoder Encodes tag data into line of tagdots. TFU Tag FIFO Unit Provides tag data storage between TE and HCU HCUHalftoner Compositor Unit Dithers contone layer and composites thebi-level spot and position tag dots. DNC Dead Nozzle CompensatorCompensates for dead nozzles by color redundancy and error diffusingdead nozzle data into surrounding dots. DWU Dotline Writer Unit Writesout the 6 channels of dot data for a given printline to the line storeDRAM LLU Line Loader Unit Reads the expanded page image from line store,formatting the data appropriately for the bi- lithic printhead. PHIPrintHead Interface Responsible for sending dot data to the bi-lithicprintheads and for providing line synchronization between multipleSoPECs. Also provides test interface to printhead such as temperaturemonitoring and Dead Nozzle Identification.Printhead Mechanical

In the preferred form, a Memjet printer has two printhead integratedcircuits that are mounted adjacent each other to form a pagewidthprinthead. Typically, the printhead ICs can vary in size from 2 inchesto 8 inches, so several combinations can be used to produce, say, an A4pagewidth printhead. For example two printhead ICs of 7 and 3 inches, 2and 4 inches, or 5 and 5 inches could be used to create an A4 printhead(the notation is 7:3). Similarly 6 and 4 (6:4) or 5 and 5 (5:5)combinations can be used. An A3 printhead can be constructed from 8 and6-inch printhead integrated circuits, for example. For photographicprinting, particularly in camera, smaller printheads can be used. Itwill also be appreciated that a single printhead integrated circuit, ormore than two such circuits, can also be used to achieve the requiredprinthead width.

A preferred printhead embodiment will now be described with reference toFIGS. 33 to 43. As best shown in FIGS. 33 to 35 and FIG. 42, a printhead420 takes the form of an elongate unit. As best shown in FIG. 42, thecomponents of the printhead 420 include a support member 421, a flexiblePCB 422, an ink distribution molding 423, an ink distribution plate 424,a MEMS printhead comprising first and second printhead integratedcircuits (ICs) 425 and 426, and busbars 427.

The support member 421 is can be formed from any suitable material, suchas metal or plastic, and can be extruded, molded or formed in any otherway. The support member 421 should be strong enough to hold the othercomponents in the appropriate alignment relative to each other whilststiffening and strengthening the printhead as a whole.

The flexible PCB extends the length of the printhead 420 and includesfirst and second electrical connectors 428 and 429. The electricalconnectors 428 and 429 correspond with the flexible connectors 147 shownFIG. 22. The electrical connectors include contact areas 148 and 159that, in use, are positioned in contact with corresponding outputconnectors (not shown) from the SoPEC chip 166 (FIG. 21). Data from theSoPEC chip 166 passes along the electrical connectors 428 and 429, andis distributed to respective ends of the first and second printhead ICs425 and 426.

As shown in FIG. 43, the ink distribution molding 423 includes aplurality of elongate conduits 430 that distribute fluids (ie, coloredinks, infrared ink and fixative) and pressurized air from the air pumpalong the length of the printhead 420 (FIG. 42). Sets of fluid apertures431 (FIG. 39) disposed along the length of the ink distribution molding423 distribute the fluids and air from the conduits 430 to the inkdistribution plate 424. The fluids and air are supplied via nozzles 440formed on a plug 441 (FIG. 35), which plugs into a corresponding socket(not shown) in the printer.

The distribution plate 424 is a multi-layer construction configured totake fluids provided locally from the fluid apertures 431 and distributethem through smaller distribution apertures 432 into the printhead ICs425 and 426 (as shown in FIG. 39).

The printhead ICs 425 and 426 are positioned end to end, and are held incontact with the distribution plate 424 so that ink from the smallerdistribution apertures 432 can be fed into corresponding apertures (notshown) in the printhead ICs 425 and 426.

The busbars 427 are relatively high-capacity conductors positioned toprovide drive current to the actuators of the printhead nozzles(described in detail below). As best shown in FIGS. 39 to 41, thebusbars 427 are retained in position at one end by a socket 433, and atboth ends by wrap-around wings 434 of the flexible PCB 422. The busbarsalso help hold the printhead ICs 425 in position, as best shown in FIGS.38, 40 and 41.

As shown best in FIGS. 40, 41 and 42, when assembled, the flexible PCB422 is effectively wrapped around the other components, thereby holdingthem in contact with each other. Notwithstanding this binding effect,the support member 421 provides a major proportion of the requiredstiffness and strength of the printhead 420 as a whole.

Printhead CMOS

Turning now to FIGS. 4 to 7, a preferred embodiment of the printhead 420(comprising printhead ICs 425 and 426) will be described. For clarity,only one printhead IC 425 is shown in FIG. 4, but it will be appreciatedthat a corresponding arrangement is implemented for the printhead IC426.

FIG. 4 shows an overview of printhead IC 425 and its connections to theSoPEC device 166. Printhead IC 425 includes a nozzle core array 401containing the repeated logic to fire each nozzle, and nozzle controllogic 402 to generate the timing signals to fire the nozzles. The nozzlecontrol logic 402 receives data from the SoPEC chip 166 via a high-speedlink. In the preferred form, a single SoPEC chip 166 feeds the twoprinthead ICs 425 and 426 with print data.

The nozzle control logic 402 is configured to send serial data to thenozzle array core for printing, via a link 407, which for printhead 425is the electrical connector 428. Status and other operationalinformation about the nozzle array core 401 is communicated back to thenozzle control logic via another link 408, which is also provided on theelectrical connector 428.

The nozzle array core 401 is shown in more detail in FIGS. 5 and 6. InFIG. 5, it will be seen that the nozzle array core comprises an array ofnozzle columns 501. The array includes a fire/select shift register 502and up to 6 color channels, each of which is represented by acorresponding dot shift register 503.

As shown in FIG. 6, the fire/select shift register 502 includes forwardpath fire shift register 600, a reverse path fire shift register 601 anda select shift register 602. Each dot shift register 503 includes an odddot shift register 603 and an even dot shift register 604. The odd andeven dot shift registers 603 and 604 are connected at one end such thatdata is clocked through the odd shift register 603 in one direction,then through the even shift register 604 in the reverse direction. Theoutput of all but the final even dot shift register is fed to one inputof a multiplexer 605. This input of the multiplexer is selected by asignal (corescan) during post-production testing. In normal operation,the corescan signal selects dot data input Dot[x] supplied to the otherinput of the multiplexer 605. This causes Dot[x] for each color to besupplied to the respective dot shift registers 503.

A single column N will now be described with reference to FIG. 6. In theembodiment shown, the column N includes 12 data values, comprising anodd data value 606 and an even data value 607 for each of the six dotshift registers. Column N also includes an odd fire value 608 from theforward fire shift register 600 and an even fire value 609 from thereverse fire shift register 601, which are supplied as inputs to amultiplexer 610. The output of the multiplexer 610 is controlled by theselect value 611 in the select shift register 602. When the select valueis zero, the odd fire value is output, and when the select value is one,the even fire value is output.

Each of the odd and even data values 606 and 607 is provided as an inputto corresponding odd and even dot latches 612 and 613 respectively.

Each dot latch and its associated data value form a unit cell, such asunit cell 614. A unit cell is shown in more detail in FIG. 7. The dotlatch 612 is a D-type flip-flop that accepts the output of the datavalue 606, which is held by a D-type flip-flop 614 forming an element ofthe odd dot shift register 603. The data input to the flip-flop 614 isprovided from the output of a previous element in the odd dot shiftregister (unless the element under consideration is the first element inthe shift register, in which case its input is the Dot[x] value). Datais clocked from the output of flip-flop 614 into latch 612 upon receiptof a negative pulse provided on LsyncL.

The output of latch 612 is provided as one of the inputs to athree-input AND gate 615. Other inputs to the AND gate 615 are the Frsignal (from the output of multiplexer 610) and a pulse profile signalPr. The firing time of a nozzle is controlled by the pulse profilesignal Pr, and can be, for example, lengthened to take into account alow voltage condition that arises due to low battery (in abattery-powered embodiment). This is to ensure that a relativelyconsistent amount of ink is efficiently ejected from each nozzle as itis fired. In the embodiment described, the profile signal Pr is the samefor each dot shift register, which provides a balance betweencomplexity, cost and performance. However, in other embodiments, the Prsignal can be applied globally (ie, is the same for all nozzles), or canbe individually tailored to each unit cell or even to each nozzle.

Once the data is loaded into the latch 612, the fire enable Fr and pulseprofile Pr signals are applied to the AND gate 615, combining to thetrigger the nozzle to eject a dot of ink for each latch 612 thatcontains a logic 1.

The signals for each nozzle channel are summarized in the followingtable:

Name Direction Description d Input Input dot pattern to shift registerbit q Output Output dot pattern from shift register bit SrClk InputShift register clock in - d is captured on rising edge of this clockLsyncL Input Fire enable - needs to be asserted for nozzle to fire PrInput Profile - needs to be asserted for nozzle to fire

As shown in FIG. 7, the fire signals Fr are routed on a diagonal, toenable firing of one color in the current column, the next color in thefollowing column, and so on. This averages the current demand byspreading it over 6 columns in time-delayed fashion.

The dot latches and the latches forming the various shift registers arefully static in this embodiment, and are CMOS-based. The design andconstruction of latches is well known to those skilled in the art ofintegrated circuit engineering and design, and so will not be describedin detail in this document.

The combined printhead ICs define a printhead having 13824 nozzles percolor. Therefore, in the case where the printhead ICs 425 and 426 areequal in length, each of them includes 6912 nozzles per color. Thecircuitry supporting each nozzle is the same, but the pairing of nozzleshappens due to physical positioning of the MEMS nozzles; odd and evennozzles are not actually on the same horizontal line.

Power and ground are provided via pads disposed along the length of theprinthead ICs. The pads are connected to busbars 427 using conductiveadhesive, as described above.

Printhead Nozzles and Actuators

The preferred printhead nozzle arrangement, comprising a nozzle andcorresponding actuator, will now be described with reference to FIGS. 46to 55. FIG. 47 shows an array of the nozzle arrangements 801 formed on asilicon substrate 8015. The nozzle arrangements are identical, but inthe preferred embodiment, different nozzle arrangements are fed withdifferent colored inks and fixative. It will be noted that rows of thenozzle arrangements 801 are staggered with respect to each other,allowing closer spacing of ink dots during printing than would bepossible with a single row of nozzles. The multiple rows also allow forredundancy (if desired), thereby allowing for a predetermined failurerate per nozzle.

Each nozzle arrangement 801 is the product of an integrated circuitfabrication technique. In particular, the nozzle arrangement 801 definesa micro-electromechanical system (MEMS).

For clarity and ease of description, the construction and operation of asingle nozzle arrangement 801 will be described with reference to FIGS.46 to 54.

Each of the ink jet printhead chips 425, 426 includes a silicon wafersubstrate 801. 0.35 Micron 1 P4M 12 volt CMOS microprocessing circuitryis positioned on the silicon wafer substrate 8015.

A silicon dioxide (or alternatively glass) layer 8017 is positioned onthe wafer substrate 8015. The silicon dioxide layer 8017 defines CMOSdielectric layers. CMOS top-level metal defines a pair of alignedaluminium electrode contact layers 8030 positioned on the silicondioxide layer 8017. Both the silicon wafer substrate 8015 and thesilicon dioxide layer 8017 are etched to define an ink inlet channel8014 having a generally circular cross section (in plan). An aluminiumdiffusion barrier 8028 of CMOS metal 1, CMOS metal 2/3 and CMOS toplevel metal is positioned in the silicon dioxide layer 8017 about theink inlet channel 8014. The diffusion barrier 8028 serves to inhibit thediffusion of hydroxyl ions through CMOS oxide layers of the drivecircuitry layer 8017.

A passivation layer in the form of a layer of silicon nitride 8031 ispositioned over the aluminium contact layers 8030 and the silicondioxide layer 8017. Each portion of the passivation layer 8031positioned over the contact layers 8030 has an opening 8032 definedtherein to provide access to the contacts 8030.

The nozzle arrangement 801 includes a nozzle chamber 8029 defined by anannular nozzle wall 8033, which terminates in a nozzle rim 804 that iscircular in plan. The ink inlet channel 8014 is in fluid communicationwith the nozzle chamber 8029. At a lower end of the nozzle wall, thereis disposed a moving rim 8010, that includes a moving seal lip 8040. Anencircling wall 8038 surrounds the movable nozzle, and includes astationary seal lip 8039 that, when the nozzle is at rest as shown inFIG. 46, is adjacent the moving rim 8010. A fluidic seal 8011 is formeddue to the surface tension of ink trapped between the stationary seallip 8039 and the moving seal lip 8040. This prevents leakage of ink fromthe chamber whilst providing a low resistance coupling between theencircling wall 8038 and the nozzle wall 8033.

As best shown in FIG. 47, a plurality of radially extending recesses8035 is defined in the roof 8034 about the nozzle rim 804. The recesses8035 serve to contain radial ink flow as a result of ink escaping pastthe nozzle rim 804.

The nozzle wall 8033 forms part of a lever arrangement that is mountedto a carrier 8036 having a generally U-shaped profile with a base 8037attached to the layer 8031 of silicon nitride.

The lever arrangement also includes a lever arm 8018 that extends fromthe nozzle walls and incorporates a lateral stiffening beam 8022. Thelever arm 8018 is attached to a pair of passive beams 806, formed fromtitanium nitride (TiN) and positioned on either side of the nozzlearrangement, as best shown in FIGS. 49 and 54. The other ends of thepassive beams 806 are attached to the carrier 8036.

The lever arm 8018 is also attached to an actuator beam 807, which isformed from TiN. It will be noted that this attachment to the actuatorbeam is made at a point a small but critical distance higher than theattachments to the passive beam 806.

As best shown in FIGS. 49 and 52, the actuator beam 807 is substantiallyU-shaped in plan, defining a current path between the electrode 809 andan opposite electrode 8041. Each of the electrodes 809 and 8041 areelectrically connected to respective points in the contact layer 8030(shown in FIGS. 46 and 51). As well as being electrically coupled viathe contacts 809, the actuator beam is also mechanically anchored toanchor 808. The anchor 808 is configured to constrain motion of theactuator beam 807 to the left of FIGS. 46 to 48 when the nozzlearrangement is in operation.

The TiN in the actuator beam 807 is conductive, but has a high enoughelectrical resistance that it undergoes self-heating when a current ispassed between the electrodes 809 and 8041. No current flows through thepassive beams 806, so they do not expand.

In use, the device at rest is filled with ink 8013 (FIG. 46) thatdefines a meniscus 803 under the influence of surface tension. The inkis retained in the chamber 8029 by the meniscus, and will not generallyleak out in the absence of some other physical influence.

As shown in FIG. 47, to fire ink from the nozzle, a current is passedbetween the contacts 809 and 8041, passing through the actuator beam807. The self-heating of the beam 807 due to its resistance causes thebeam to expand. The dimensions and design of the actuator beam 807 meanthat the majority of the expansion in a horizontal direction withrespect to FIGS. 46 to 48. The expansion is constrained to the left bythe anchor 808, so the end of the actuator beam 807 adjacent the leverarm 8018 is impelled to the right.

The relative horizontal inflexibility of the passive beams 806 preventsthem from allowing much horizontal movement with respect to the leverarm 8018. However, the relative displacement of the attachment points ofthe passive beams and actuator beam respectively to the lever arm causesa twisting movement that causes the lever arm 8018 to move generallydownwards. The movement is effectively a pivoting or hinging motion.However, the absence of a true pivot point means that the rotation isabout a pivot region defined by bending of the passive beams 806.

The downward movement (and slight rotation) of the lever arm 8018 isamplified by the distance of the nozzle wall 8033 from the passive beams806. The downward movement of the nozzle walls and roof causes apressure increase within the chamber 8029, causing the meniscus to bulgeas shown in FIG. 47. It will be noted that the surface tension of theink means the fluid seal 8011 is stretched by this motion withoutallowing ink to leak out.

As shown in FIG. 48, at the appropriate time, the drive current isstopped and the actuator beam 807 quickly cools and contracts. Thecontraction causes the lever arm to commence its return to the quiescentposition, which in turn causes a reduction in pressure in the chamber8029. The interplay of the momentum of the bulging ink and its inherentsurface tension, and the negative pressure caused by the upward movementof the nozzle chamber 8029 causes thinning, and ultimately snapping, ofthe bulging meniscus to define an ink drop 802 that continues upwardsuntil it contacts adjacent print media.

Immediately after the drop 802 detaches, the meniscus forms the concaveshape shown in FIG. 48. Surface tension causes the pressure in thechamber 8029 to remain relatively low until ink has been sucked upwardsthrough the inlet 8014, which returns the nozzle arrangement and the inkto the quiescent situation shown in FIG. 48.

As best shown in FIG. 49, the nozzle arrangement also incorporates atest mechanism that can be used both post-manufacture and periodicallyafter the printhead is installed. The test mechanism includes a pair ofcontacts 8020 that are connected to test circuitry (not shown). Abridging contact 8019 is provided on a finger 8043 that extends from thelever arm 8018. Because the bridging contact 8019 is on the oppositeside of the passive beams 806, actuation of the nozzle causes thepriding contact to move upwardly, into contact with the contacts 8020.Test circuitry can be used to confirm that actuation causes this closingof the circuit formed by the contacts 8019 and 8020. If the circuitclosed appropriately, it can generally be assumed that the nozzle isoperative.

Flat Panel Display Device with Integrated Printer

A preferred embodiment of the invention is shown in FIGS. 8 to 25.Referring particularly to FIGS. 8 to 15, a flat panel display unit 141includes a flat panel display 142 that is supported on a stand 143. Thepresent invention primarily applies to flat panel displays where aviewable size of the flat panel display exceeds 40 cm measured along adiagonal of the flat panel display. The stand 143 includes a baseportion 144, which supports an arm 145 to which a housing 146 for thedisplay 142 is hingedly connected. Various control buttons 148 areprovided on the display unit 141, for controlling display functions suchas contrast, brightness, color temperature and the like.

The display unit 141 incorporates a page-width printer (described below)that accepts, in the preferred embodiments shown in FIGS. 8 to 32,single sheets of standard A4 or US Letter paper 149. A curved paperguide 150 causes paper exiting the printer to be directed away from thebase 144 of the display unit 141, as best shown in FIGS. 9 and 12.

The sub-components that comprise the display unit 141 are shown inexploded view in FIG. 16. A mounting plate 151 is hingedly mounted tothe arm 145 and attached to a rear cover molding 152 formed from aplastics material. The cover molding is perforated to allow convectiveair currents to cool the electronic circuitry inside the display unit141.

A metallic radio frequency interference and electromagnetic interference(RFI/EMI) shield 153 fits inside the concave side of the rear covermolding 152. The shield 153 screens the various circuitry elements fromexternal radiation, whilst reducing any radiation generated by thecircuitry being transmitted from the display unit 141. The shield 153takes the form of a cage with cooling holes that allow ventilation ofthe circuitry. An additional shield 154 covers the printhead (describedbelow in relation to FIG. 23).

The various electronic, mechanical and electromechanical components thatcomprise the printer are mounted on interconnected printed circuitboards (PCBs) 155, as best shown in FIGS. 19 to 21. The PCBs 155 includea printhead PCB 156, an analog converter PCB 157, a backlight inverterPCB 158, and a power supply unit (PSU) 159. The PSU 159 supplies powerat appropriate voltage and current to the various other PCBs via wiring160.

Turning to FIG. 22, the printhead PCB forms part of a print engineassembly 161. The print engine assembly 161 also includes paper feedrollers 162, a platen 163 for supporting paper as it is fed past theprinthead, an air pump 164 for supplying pressurized air to theprinthead, a flexible connector 147 for supplying data from the printengine chips on the print engine PCB to the printhead, an ink deliverybus 165, and a print engine controller (SoPEC) chip 166. The feedrollers 162 are driven by a paper drive motor 197 and drive assembly198.

As shown in FIG. 23 (in which the platen and feed rollers are removedfor clarity), the print engine assembly 161 also includes supportmetalwork 167 for mounting the various components, copper busbars 168for supplying power from the power leads 169 to the printheads, andflexible paper guide fingers 170. Ink channel moldings 171 route inkfrom the ink delivery bus 165, which also includes electrical contacts173 that enable communication between an ink cartridge (described below)and the print engine assembly. It will be noted that the presentembodiment includes two printhead segments 174 and 175 of equal lengththat together form a pagewidth printhead. As described earlier in thisdocument.

Referring back to FIG. 16, a metal paper chute 176 is provided to guidepaper behind the display and down to the printhead. A metal chassis 177is provided to support the display 142, which is surrounded andprotected by a plastic front bezel molding 178. A menu PCB 179 holds themenu buttons 148 and associated status LEDs.

As best shown in FIG. 10, the display unit 141 is provided with powervia a mains cord 180 and associated mains plug 181. The mains plug 181is inserted into mains socket 182, which is shown in FIG. 17 with themains plug 181 removed. The mains socket 182 is hard-wired into the PSU159.

A video input cable 183 and associated video plug 184 supply video datafrom a computer. The video plug 184 is inserted into a video socket 185,which is shown in FIG. 17 with the video plug 184 removed for clarity.

A data connection in the form of a USB 2 link is provided by way of adata cable 186 and associated data plug 187. The plug 187 is insertedinto a USB 2 compliant data socket 188, which is shown in FIG. 17 withthe data plug 187 removed for clarity.

As shown in FIG. 21 an ink cartridge 189 containing the various inksrequired for operation of the printer releasably engages the inkdelivery bus 165 via an aperture 190 (FIG. 16) formed in the rearmolding 152. The cartridge is preferably held in position by aninterference fit, although a positive retaining mechanism such as a clipcan be supplied in alternative embodiments. As best shown in FIG. 21,the ink delivery bus 165 includes a plurality of fluid ports 191 thatengage with corresponding fluid outputs (not shown) formed in thecartridge. In the embodiment shown, each fluid port 191 includes ahollow needle 192 that penetrates a seal (not shown) in thecorresponding fluid output. The seal can be an annular resilient sealwith a frangible membrane, or simply a frangible membrane thatself-seals around the needle 192 as the cartridge 189 is inserted intoan operative position.

The cartridge 189 contains the inks necessary for its use with theprinter. The various possible combinations of colored inks (such asCMY), black ink, infrared ink and a fixative are described elsewhere inthis document. The cartridge 189 also includes a QA (“Question-Answer”)chip that is configured to store information accessible by the SoPECchip 166, such as ink levels remaining (preferably on a per-ink basis),types of ink contained in the cartridge, security data for ensuring thecartridge is compliant with the printer's needs and any other data thatmight be useful for the operation of the printer based on the particularcartridge inserted. The QA chip is electrically connected to a set ofcontacts (not shown) that operatively engage the electrical contacts 173on an edge of the ink delivery bus 165. The electrical contacts allowinformation to be read from the QA chip in the cartridge 189 asrequired. This can be when the cartridge is first inserted, and possiblyperiodically thereafter. In the preferred embodiment, the SoPEC chip 166can also write back to the cartridge. Typically, this will involvedetermining the amount of ink used and then updating the QA chip in thecartridge.

A number of other elements of the display unit 141 not shown in otherFigures are shown in FIG. 44. It will be noted that the flat paneldisplay 142 is preferably a Thin Film Transistor (TFT) Liquid CrystalDisplay (LCD). However, it will be understood that the particulartechnology employed in the flat panel display 142 is not critical to theinvention. The flat panel display 142 can therefore be of any othertype, including those using Organic Light Emitting Diode (OLED), FieldEmission Display (FED) and Plasma Display Panel (PDP) technologies.

As shown in FIG. 44 the display unit includes row drivers 193 and columndrivers 194 that are provided with input signals by an image processor195 located on the analog converter PCB 157. The image processorreceives display data from a personal computer (not shown) via the videosocket 185. The fluorescent backlight inverter PCB 158 drives afluorescent backlight 196.

The USB input 188 (FIG. 17) provides data in accordance with the USB 2protocol to the SoPEC chip 166. The image processor 195 can also providedata to the SoPEC chip 166, as described in detail below.

Operation of the display unit will now be described with reference toFIG. 44. Display data is received from a personal computer, or othersuitable video data source, via the video input socket 185. The displaydata is provided to the image processor 195, which processes andconverts it into a format suitable for supply to the row drivers 193 andcolumn drivers 194. These drive the various TFTs required to display theimage on the flat panel display 142. The fluorescent backlight 196provides illumination from behind the TFTs, thereby enhancing visibilityof images displayed. Various display settings, such as contrast,brightness and resolution, can be altered by a user via the controls148.

The USB input socket 188 accepts USB formatted data from a connectedpersonal computer, such as personal computer 102 in FIG. 1. It will beappreciated that this data can come from any other suitable source, suchas a network connection or any other data communication link.

Upon receipt, the data is forwarded via an internal USB link to theprinthead PCB 156 and the SoPEC chip 166. The data is decompressed andformatted in accordance with the steps shown in FIG. 1, using thehardware 232 described in relation to FIG. 2. The formatted data isforwarded from the SoPEC chip 166 to the Memjet printheads 174 and 175.The data is then printed onto the paper 149 as it is driven past theprintheads.

In the preferred embodiment, the print button 200 (FIGS. 8 and 9) can beused to generate a printout of the presently displayed image. Thisenables a printout of the screen to be taken without the need to use amouse, keyboard or other control device associated with the personalcomputer 102.

The invention has a number of advantages over the prior art. Thecombination of a printer and flat panel display saves a considerableamount of room compared to a separate display and printer combination.The printed matter, in the preferred embodiment, is ejected right infront of the user, unlike the case with prior art printers which are,for the most part, too bulky to be placed directly in front of the user.

In the particularly preferred embodiment described, the pagewidth natureof the printer and its relatively compact dimensions compared withinkjet and laser printers respectively mean that high quality printingcan be provided without substantially increasing the size of the flatpanel display casing. Given that a major advantage of flat paneldisplays is their compactness, this can be considered a major feature ofthe preferred embodiment. With the use of a pagewidth printhead, thereis less vibration than with a reciprocating inkjet printhead, resultingin a more stable image for a user viewing the display whilst printing.

An alternative embodiment of the invention is shown in FIG. 26, in whichlike numerals indicate features corresponding to those described inrelation to the embodiment of FIGS. 8 to 25. The embodiment of FIG. 26is a duplex printer, which includes a pair printheads 304 and 305. Theprintheads are preferably of the same construction as the singleprinthead, each comprising two printhead segments. In the preferredembodiment, each of the printheads 304 and 305 has its own associatedSoPEC device.

In operation, the embodiment of FIG. 26 prints onto both sides of thepaper 149 as it is fed between the printheads 304 and 305.

A further embodiment is shown in FIGS. 27 and 28, in which like numeralsindicate features corresponding to those described in relation to theembodiment of FIGS. 8 to 25. The embodiment includes a multi-sheetfeeder 312 that enables a single sheet at a time to be taken from astack of paper and fed past the printhead. The feeder 312 is best shownin FIG. 28, and includes a paper stop 205 that holds a stack of paper203 in position. The preferred capacity of the stack 203 is about 50sheets, although other capacities can be used. A flexible shim 206extends across the top of the paper stop 205, terminating in an edgeadjacent and below a pickup roller 204. The pickup roller 204 isgenerally circular in cross-section, but incorporates a flat portion313.

In use, the paper stack 203 is loaded such that it rest on the flexibleshim 206, which is in turn supported by the paper stop 205. The pickuproller 204 is positioned rotationally such that the flat portion 313(FIG. 28) is aligned with the nearest piece of paper in the stack. Thepickup roller 204 is then rotated clockwise (relative to FIG. 28), untilthe rounded portion engages the piece of paper. As this happens,friction between the paper and the roller increases, causing a downwardforce on the paper. The flexible shim 206 causes the sheet of paper tobe separated from the stack 203 and driven downwards towards the feedrollers 162. As the paper engages the feed rollers, the flat spotrotates back into the position shown in FIG. 28, which reduces thefriction between the pickup roller and the paper, thereby enabling thefeed rollers to push the paper past the printhead.

It will be appreciated that any other known paper feeding mechanisms canbe employed for taking a single sheet from a stack and feeding it forprinting. It will also be appreciated that a duplex printheadarrangement such as that shown in FIG. 26 can also be employed with amulti-sheet feed mechanism.

Another embodiment is shown in FIG. 29, in which the sockets 182, 185and 188 are positioned in the base portion 144 of the display unit. Thisenables a neater arrangement of cables, since there is no need to routethem all the way up to the rear molding 152. Rather, internal wiringtakes the power and data from the sockets to the relevant components viathe interior of the arms 145.

FIG. 30 shows another embodiment, in which the base portion 144 acts asa data hub. Circuitry (not shown) in the base portion 144 allows the USBconnection enabled by socket 188 to send and receive data to and fromother devices via data hub connectors 207. This enables anything fromnetwork to peripheral devices to be connected via the base portion 144,rather than needing to access ports or sockets on the personal computerto which the display unit is connected. This can be advantageous giventhat ports and sockets on personal computers are often positioned inrelatively difficult to access places. Often, the computer device itselfis positioned out of the way, such as underneath a desk, which cancontribute to this inconvenience of making data connections in the priorart.

Yet another embodiment, shown in FIG. 31, the ink bus 165 is positionedsuch that the ink cartridge 189 is positioned on the mounting plate 151.

FIG. 32 shows another embodiment of the invention, in which the inkcartridge 189 is positioned in the base portion 144 of the display unit.In this case, the arms 145 also include ink conduits for supplying inkfrom the cartridge 189 to the printer. In some cases, it may benecessary to provide some form of pump or other pressurizationarrangement to push the ink upwards through the conduits in the arms145.

One Touch Print Button

A desktop printer attached to a personal computer (PC) may usefullyincorporate an “Print” button which when pressed causes the activeWindows application on the PC to print its entire active document to theprinter, without an intervening print dialog.

As a variation on this theme, when the printer is embedded in aflat-panel display (FPD), then the Print button may be incorporated inthe display.

By active application we mean the application whose window is top-most,and with which the user it typically currently interacting. By activedocument we mean the document displayed in the active application'stop-most window.

When the Print button is incorporated in a printer, it is important thatthe button initiates printing to that printer. When the Print button isincorporated in a display, it is reasonable for it to initiate printingto the default printer, which may or may not be configured to be thein-panel printer.

Windows Printing Background

There is no single standard way under Microsoft Windows toprogrammatically instruct the active application to print its activedocument to the default or to a designated printer. However, there areseveral mechanisms which may be exploited, covering most applicationtypes.

Although not explored here, comparable mechanisms exists under otheroperating systems and windowing systems, including Apple MacOS, Unix, XWindows, Linux etc. It should be appreciated by those skilled in the artthat the invention is not limited to use with any particular hardware,operating system or software combination.

Printing User Interface

Most Microsoft Windows applications, as a matter of convention, providea fairly standard printing user interface. This consists of: (a) a Printoption on the File menu, usually accessible via the two keyboardsequences ALT, F, P and CTRL+P, which displays a print dialog to printthe current document; and (b) a Print tool on the toolbar (shown as aprinter icon) which prints the current document to the default printerwithout displaying the print dialog. Dialog-less direct printing has nostandard keyboard shortcut.

If the active application is receptive to a keyboard sequence in thisway, then a client application can instruct it to print by queuing theappropriate keyboard events (using the keybd_event or SendInput SDKfunctions) or by queuing the appropriate keyboard messages (using theAttachThreadInput, GetFocus, and PostMessage SDK functions). Directprinting can be simulated by appending a carriage-return to the keyboardsequence, causing the print dialog to be completed without further userinput.

Automation

Some Windows applications, including Microsoft Office applications suchas Word and Excel, expose an Automation interface (formerly known as OLEAutomation), which allows them to be controlled by a separateapplication. For example, Word (like many other Microsoft applications)exposes a PrintOut method which can be invoked on the active document toprint the document directly. A client application can discover an openWord document and print it in this way. The application can designate aparticular printer by assigning the name of the printer to Word'sActivePrinter property prior to invoking the PrintOut method.

Automation servers such as Office applications register runninginstances of themselves in the Running Object Table (ROT).Multi-instance applications (such as Excel and some versions of Word)are only able to create a single application entry in the ROT. However,multi-instance applications typically also register each of their opendocuments separately in the ROT, allowing the client application to findthe application instance corresponding to a particular document via thedocument's entry in the ROT.

The client application can iterate through the ROT, attach to eachserver application of interest in turn, and identify whether theapplication is associated with the foreground window. If the serverapplication is associated with the foreground window (as identified bythe GetForegroundWindow SDK function), then the client application caninvoke the application's PrintOut method (or equivalent) to print theactive document.

In the case of a single-instance application (such as PowerPoint), theclient application attaches to the server application directly via theROT entry. In the case of a multi-instance application (such as Excel),the client application attaches to the server application via a documententry in the ROT.

The Windows SDK provides standard functions for obtaining a pointer tothe ROT and iterating through it. Application and document entries inthe ROT are easily recognised since each entry is associated with aclass-specific programmatic identifier. For example, a Word applicationhas the programmatic identifier “Word.Application.x” (where x indicatesthe application version), and a Word document has the identifier“Word.Document.y” (where y indicates the document version). Anapplication entry in the ROT conventionally includes the application'sclass identifier in its name, from which the corresponding programmaticidentifier can be obtained via the Windows registry. A document entry inthe ROT allows its programmatic identifier to be discovered via theclass identifier associated with the document's persistence interface.

Because there are several ways to programmatically instruct the currentapplication to print its active document to the default or to adesignated printer, and because no single way is optimal for allapplications, support for a “Print” button is best provided (in thisembodiment) by invoking the mechanism most appropriate to the currentapplication according to the current application's type.

In its simplest form, this consists of first trying to find the activeapplication in the ROT, specifying the target printer by setting theactive application's ActivePrinter property, and invoking the activeapplication's PrintOut method. If the active application is not found inthe ROT, then the fallback consists of queuing the standardprint-invocation keyboard sequence (i.e. Control key down, P key down, Pkey up, Control key up, CR key down, CR key up).

In a more sophisticated implementation, a table of applications iscreated which lists the mechanism most appropriate to each applicationtype, i.e. Automation versus keyboard sequence, and exact applicationproperties and methods to use, or exact keyboard sequence to send.Automation server applications are identified by their programmaticidentifiers, while conventional applications are identified by theirnames. For example, Word is identified by its programmatic identifier“Word.Application.x”, while Notepad is identified by its name “Notepad”.It is straightforward to identify the foreground window (via theGetForegroundWindow SDK function) and extract the name of thecorresponding active application from the window's title (via theGetWindowText SDK function).

The “Print” button can be a physical momentary switch or it can besimulated via another interface on the printer (or FPD) such as atouch-sensitive display. In any case, when the user presses the printbutton, an event is relayed to a background application on the PC whichinvokes the corresponding printing function as described above. Thebackground application may already be executing, i.e. awaiting events,or it may be activated by the user's act of pressing the “Print” button.The button event can be relayed by the control software in the printer,via the printer's communications interface and its printer driver, andthence to the background application. Alternatively can be relayed viaits own communications interface and driver, in which case the driverand the background application may be one and the same. For example, theprint button can be provided in the form of a separate Universal SerialBus (USB) device on the USB bus, but may share the physical USBconnection between the printer (or FPD) and the PC.

In the preferred embodiment, the background application is capable ofhandling the “Print” buttons of multiple devices. To allow it todistinguish multiple buttons, each button event in this embodimentuniquely identifies its originating button. An event may include aunique identifier associated with the printer in which the button isembedded, or a unique identifier associated with the button itself,retrieved from non-volatile storage attached to the button. In caseswhere the target printer can be selected by setting the active serverapplication's ActivePrinter property, the background application mustknow which printer name to specify. Since it may be difficult for thebackground application to know the name of the printer associated with aparticular “Print” button it is servicing, it is useful to allow theuser to associate a printer with each button, indexed by the button'sunique identifier. If a button is pressed which has no associatedprinter, then the background application can determine how many printersare configured on the PC. If there is only one printer, then theapplication has no need to specify a printer since the one printer mustbe the default printer. If there are several printers, then theapplication can prompt the user to select one, and can then record theassociation between the selected printer and the button. It isstraightforward for the background application to enumerate theavailable printers using the EnumPrinters SDK function.

Various exemplary, non-limiting aspects of the invention areforeshadowed in the following numbered paragraphs:

1. A stand alone monitor for connecting to an external computer, themonitor comprising: a housing detached from the external computer; aflat panel display disposed in the housing for displaying data videosignal provided by the external computer; a pagewidth inkjet printheadfor printing print data provided by the external computer onto a papersheet, the pagewidth inkjet printhead being disposed in the housingbehind the flat panel display as viewed by a user; a video connection toallow releasable operative connection of the external computer to themonitor for receiving the video signal; a data connection to allowreleasable operative connection of the external computer to the monitorfor receiving the print data; and a stand for holding the flat paneldisplay in an operative position, the stand including at least onereceptacle configured to accept at least one replaceable ink cartridgefor supplying ink to the printhead.
 2. A stand alone monitor as claimedin claim 1, comprising at least two printheads, the printheads beingdisposed on either side of a path through which the paper sheet is fedfor printing, thereby enabling substantially simultaneous printing ofboth sides of the paper sheet.
 3. A stand alone monitor as claimed inclaim 1, further comprising a paper feed mechanism configured toposition the paper sheet substantially parallel in at least onedirection with respect to a plane defined by the flat panel display. 4.A stand alone monitor as claimed in claim 1, wherein the printhead is aprocess color printhead.
 5. A stand alone monitor as claimed in claim 1,wherein the printhead has more than 5,000 inkjet nozzles.
 6. A standalone monitor as claimed in claim 1, further including a curved paperguide disposed, when the monitor is in use, beneath the flat paneldisplay, such that the paper sheet that has been printed is urgedhorizontally as the paper sheet exits the monitor.
 7. A stand alonemonitor as claimed in claim 1, wherein the printhead is configured toreceive halftoned print data to be printed onto the paper sheet.
 8. Astand alone monitor as claimed in claim 1, further including ahalftoning unit for generating halftoned image data and supplyinghalftoned image data to the printhead for printing.
 9. A stand alonemonitor as claimed in claim 1 further comprising: a data connection hubconfigured to allow connection of at least one data-receiving device tothe monitor, enabling the data-receiving device to receive data from theexternal computer.
 10. A stand alone monitor as claimed in claim 1wherein, during printing, the paper sheet being printed onto passesbetween the flat panel display and the printhead, or passes behind theflat panel display and the printhead relative to a viewing position ofthe flat panel display.